It is the purpose of the present proposal to extend ongoing efforts in our collaborative program "Phased Arrays for Multiplane Esophageal Echos in Infants" so as to facilitate more extensive application of the unique transesophageal ultrasound probes we have developed by running them on several commercially available scanners and testing them in multiple centers. This is especially important with regards to exploring the clinical application and three dimensional reconstruction capabilities of a miniaturized rotating plane probe suitable for use in infants (maximal introduction diameter < 8.2mm) which should be completed by Dec. 1994 and will not have been other than anecdotally demonstrated and tested by the end of the funding period for the currently funded proposal. The funding of the proposed work should allow our research efforts to have achieved their original goal of providing a demonstration project for clinicians and for the medical ultrasound industry regarding the application of very high resolution ultrasound devices for monitoring heart surgeries and interventionaI catheterizations for newborns and other infants under 6 months of age as well as for proving the concept of user- friendly clinical application of 3-dimensional reconstruction displays of cardiac anatomy derived from ultrasound images in patients with complex congenital heart disorders. Technical milestones which required mastery to produce our first miniaturized transesophageal echocardiography (TEE) scanners and those required for multiplane device miniaturization at 7.5MHz have been substantial in order to keep introduction sizes small enough for newborn use but maintain high resolution apertures. Suitable arrangements for device application for probes built during this program now exist with three ultrasound instrument manufacturers and with other collaborating centers of excellence in Congenital Heart Disease Echocardiography.